best practices question on domain setup

I am about to set up a 2003 server for the first time. I'm not to familiar with Active Directory. I'm looking for some basic advice on best practices/setup. I have had experience with the NT4 server and domain environment. This server will only have about 5 users and is purchased for the sole purpose of running an accounting application. One of my concerns is the naming of the domain. The company already has a website and this server will never host it, so I believe I will just create a domain name that has nothing to do with their registered fqdn.

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